The Causes, Symptoms and Treatments for High Blood Sugar

High blood sugar levels can impact your health in a variety of ways.Getty Images

Blood sugar, also called glucose, is the sugar that circulates in your bloodstream, says Dr. Michael del Junco, an internal medicine specialist with Providence St. Joseph Hospital in Orange County, California.

“After we eat, the body digests the meal into sugars, called glucose. The sugar will travel from the stomach to the small intestine, where it’s absorbed into the bloodstream.”

That signals the pancreas, an abdominal organ that aids in digestion and hormone regulation, to release insulin. “Insulin helps glucose get transported into tissues to act as a source of fuel for the cells in your body,” del Junco explains.

Any excess sugar that does not move into the tissues gets stored in the liver and muscles as triglycerides, a type of fat.

Insulin Resistance Disrupts Normal Blood Sugar Levels

For some people, however, the pancreas doesn’t make enough insulin to efficiently move all the glucose from the blood stream to working cells throughout the body, and this can lead to elevated blood sugar levels.

“The most common consequences of chronically elevated blood sugars are metabolic syndrome, prediabetes and diabetes,” del Junco explains.

“All of these conditions are characterized by a state of insulin resistance. This is a condition where your body does not respond as it should to insulin, causing glucose levels to remain elevated in the blood,” he adds.

Symptoms of High Blood Sugar

Some high blood sugar symptoms are non-specific and can include:

  • Polyuria: an increased urge to urinate, often at night.
  • Polydipsia: increased thirst.
  • Polyphagia: an increased urge to eat.

High Blood Sugar Effects on Health

Because blood circulates throughout the entire body, too-high blood sugar levels can have negative consequences for virtually every organ system and process. Here are eight ways that chronically high blood sugar levels can adversely impact your health:

Why is it important to control your blood sugar levels? Put simply, blood reaches and influences everything in your body, says Dr. Craig Primack, president-elect of the Obesity Medicine Association.

Here, experts share eight unexpected ways high blood sugar levels can adversely impact your health:

Consider this scenario: Two people enter the emergency room complaining of chest pain. One has suffered a heart attack in the past. The other has diabetes.

Who is more likely to be having a heart attack? The one with diabetes, says Dr. Craig Primack, an obesity specialist and co-director and co-founder of the Scottsdale Weight Loss Center in Arizona. He explains this situation is commonly used in medical schools to demonstrate how diabetes acts as a “coronary artery disease equivalent.” By that, he means, “if you have diabetes, you basically already have coronary artery disease, even if it hasn’t been diagnosed,” he says.

While experts used to believe that dietary cholesterol was the main culprit behind artery-clogging plaque, current research suggests excess levels of sugar in the blood likely playing a larger role, Primack says.

This happens because high blood sugar levels increase the production of free radicals – highly reactive molecules that cause premature cell death – and reduce the availability of nitric oxide – a compound that’s needed for blood vessels to relax and allow blood to flow freely despite plaque buildup. The resulting inflammation can lead to blood vessel damage.

Heart disease is the leading cause of death among people with diabetes, according to the American Diabetes Association, which notes that two-thirds of deaths in people with Type 2 diabetes are caused by CVD.

With high blood sugar levels, the same factors that decrease blood flow to the heart reduce blood circulation to the sexual organs, Primack says.

According to a 2017 review in the journal Diabetes Medicine, about 53% of the 90,000 men with diabetes included in the study also had erectile dysfunction. The study also found that men with diabetes are 3.5 times as likely than men without the disease to have difficulty maintaining an erection. They also tended to develop ED about 10 to 15 years earlier than men who didn’t have diabetes.

Those with poorly controlled blood sugar levels are more likely to have sexual side effects compared with those who have their blood sugar under control.

While they have been less studied, women with chronically high blood sugar levels can also experience sexual issues. These issues can include vaginal dryness, low levels of sexual interest and difficulty reaching orgasm.

Either way, the link between high blood sugar and cognitive decline is strong, no matter your diabetes diagnosis. For example, a 2018 study published in the journal Diabetologia, which tracked 5,189 people over the course of 10 years, showed that the higher the blood sugar level, the faster the rate of cognitive decline.

Researchers don’t yet know the full explanation between the sugar-brain connection, but reduced blood flow is likely to play a role, Primack says.

Most people have heard of diabetic neuropathy, in which chronically high blood sugar levels damage nerve cells throughout the body, leading to a pins-and-needles sensation and even numbness in the hands, feet, arms and legs.

But here’s a lesser-known fact: This nerve damage can also deteriorate the body’s joints, explains Dr. Jeff E. Sellman, a family and sports medicine physician with the Florida Orthopedic Institute in Tampa.

Called Charcot joint or diabetic arthropathy, this arthritis-like condition can cause instability and deformations in the joints, commonly in the feet.

Meanwhile, excess glucose molecules in the blood can adhere to joint surfaces, making them stickier and less able to move smoothly. The excess glucose can also degrade collagen in the joint, leading to more joint pain and stiffness.

By damaging blood vessels in the kidneys, chronically high blood sugar levels can also reduce kidney function and contribute to renal disease. The longer someone has diabetes, and the longer that diabetes goes uncontrolled, the greater the risk of kidney disease. The National Kidney Foundation reports that about one-third of people with diabetes have chronic kidney disease.

The kidneys help balance fluid levels and remove waste from the body, and thus are vital to overall health. If you have Type 2 diabetes or have had Type 1 diabetes for more than five years, the National Institute of Diabetes and Digestive and Kidney Diseases recommends having your kidney function checked yearly.

Experts used to think it was the day-to-day doldrums of managing diabetes that increased the risk of depression in people with Type 1 and Type 2 diabetes, but emerging research suggests that blood sugar levels may be a far greater depressant than taking blood sugar readings and insulin shots.

For example, research published in the Journal of Neuroscience shows, for those with Type 1 diabetes, high blood sugar levels increase the brain’s levels of a neurotransmitter associated with depression. The study also found that high sugar levels alter connections between regions of the brain that control emotion, potentially contributing to mental health issues.

A 2021 study from Stanford University similarly found that insulin resistance, which is associated with chronic high blood sugar levels and is a precursor to diabetes, doubles the risk for major depressive disorder.

Chronic high blood sugar levels can lead to diabetic retinopathy, which can develop when blood vessels in the retina – the light-sensitive cells at the back of the eye that permit sight – become damaged. These damaged vessels sometimes swell, leak or obstruct normal blood flow. This can lead to blurry or distorted vision and blindness.

Glaucoma is also associated with diabetes. This eye disease is caused by damage to the optic nerve, usually because there’s too much pressure in the eye. It can lead to slow vision loss over time. The Centers for Disease Control and Prevention reports that people with diabetes are twice as likely to develop open-angle glaucoma, which is the most common type of glaucoma.

The CDC recommends getting a dilated eye exam at least once a year from an optometrist or ophthalmologist, as they can catch these and other vision problems related to high blood sugar. That could lead to earlier diagnosis, better control of diabetes and overall better health outcomes.

Digestive issues such as gastroparesis are common complications of high blood sugars and diabetes. Gastroparesis, also sometimes called delayed gastric emptying, is a condition in which the stomach slows or halts the movement of food into the small intestine. It can cause nausea, bloating and cramping and may lead to nutritional deficiencies. The NIDDK reports that diabetes is the most common cause of gastroparesis and occurs in about half of all patients with diabetes.

Lifestyle Interventions Can Help

“Because the majority of those with prediabetes will develop diabetes, it’s important to identify simple strategies to effectively lower blood sugar and our risk of developing these conditions,” del Junco says. While the outlook might look grim if your blood sugars have been trending too high lately, there are some lifestyle changes you can make that can help bring them back down. “The best treatments continue to remain diet and exercise.”

Del Junco also recommends the following:

  • Exercise. “Moderate intensity aerobic exercise for 150 minutes a week or 30 minutes a day can lower blood sugar by 20% to 22%” he says. “Employing this strategy alone can reduce your risk of diabetes by roughly 25%.”
  • Lose excess weight. “A weight loss of 5% to 10% of your total body weight can lower your blood sugar and risk of diabetes by 55% to 60%,” del Junco says.
  • Move more. In addition to exercising, del Junco recommends simply getting up and moving around every 30 minutes and avoiding inactivity for long periods of time.
  • Improve your diet. Del Junco recommends limiting the among of saturated fats, sugary drinks, trans fats, fried foods, ultra-processed foods, fructose and red meat in your diet. Instead, “increase your consumption of food with lower glycemic index such as fish, fiber, fruits, leafy vegetables, whole grains, nuts and natural oils.” Glycemic index is a measure of how quickly a serving of food elevates your blood sugar level. Sugary liquids like sodas have very high glycemic index ratings, while green leafy vegetables with lots of fiber that slows the movement of glucose from the food into the bloodstream are much lower on the glycemic index scale.
  • Ask your doctor. For many people, lifestyle changes aren’t enough to bring down high blood glucose levels, and you may need medications to help lower your blood sugar. Talk to your health care provider about your specific needs and what would work best to keep your blood sugars at optimal levels.


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